Problem solve Get help with specific problems with your technologies, process and projects.

Preventing a resolved internal IP address when using PC testing sites

When I go to various PC test sites my internal IP address is always resolved. Is there a way to prevent this? I'm running Win XP Home (SP2). I use McAfee VirusScan and Firewall. CounterSpy is my anti-spyware program. My ISP is Verizon DSL. My PC is not missing any patches. Should I be concerned about this or am I being too paranoid?

It kind of depends on the test site you are using and your home network configuration. If you are using an external hardware based firewall such as the Cisco PIX 501 or any of the SOHO firewall products, your internal address space (typically 192.168.1.x) should be undetectable from an outside source. If the address is being detected, it could be a sign that NAT is not properly configured on your network, and that is a legitimate concern.

If you are not using an external hardware based firewall and the IP address that is being reported is the address that Verizon is assigning you, that isn't of concern, since that address must be known on the Internet to allow for communications. I would recommend that, in addition to your current configuration, you also implement a dedicated hardware based firewall for the additional security and anonymity of your internal address space.

In regards to the test sites, the most popular site out there, www.grc.com can detect your internal IP address if you have installed a client "shim" from them. This essentially circumvents the NAT masking that occurs, allowing GRC to report on your actual internal address. If you have installed this client component, then there is nothing to worry about, since it is working as it should.

This was last published in June 2005

Dig Deeper on User passwords and network permissions

Have a question for an expert?

Please add a title for your question

Get answers from a TechTarget expert on whatever's puzzling you.

You will be able to add details on the next page.

Start the conversation

Send me notifications when other members comment.

By submitting you agree to receive email from TechTarget and its partners. If you reside outside of the United States, you consent to having your personal data transferred to and processed in the United States. Privacy

Please create a username to comment.